Patent GB-848675-A (GB)
Title: Halogen-free silica pigments, cured products containing same and method of preparation thereof
IPC: C09C1/30
Filed: 1956-12-20
Abstract: Light coloured to white, particulate, solid amorphous silica containing up to 3% by weight halogen is treated (see Group III) with one or more nitrogen compounds containing reactive hydrogen attached to the nitrogen to remove substantially all the halogen without causing sintering of the silica, and is used as a reinforcing pigment in organic polymeric compositions.  The treated silica may be treated with steam under elevated temperature to remove nitrogen, and the treated silica may be coated with alcohols, amines, or silicone resins.  A large number of organic polymers, in which the pigment may be used, are specified including natural and synthetic rubbers, such as polymers, copolymers, terpolymers, &c., of conjugated dienes, vinyl resins, acrylic resins, carboxyl-containing compounds, olefins, ester urethanes, or silicones.  The polymeric compositions contain usual compounding ingredients, and may contain 25-45% pigment to 75-55% polymer, and are cured.  In examples:-the pigment is mixed with (3) natural rubber, dianilino methane, sulphur, zinc oxide, stearic acid, pine oil, phenylbeta-naphthylamine, didodecylamine, and benzylthiazyl disulphide.  Specifications 804,991, 804,992, 828,723 and 848,674 are referred to.ALSO:Light coloured to white, particulate, solid amorphous silica containing up to 3% by weight halogen, obtained by halogenating silicon monoxide (SiO2)x Siy to remove Si, is treated with one or more nitrogen compounds containing reactive hydrogen attached to the nitrogen in an amount, and at a temperature, such as to remove substantially all the halogen without causing sintering of the silica.  The halogenated silicon monoxide, which is preferably substantially fibrous, is prepared according to Specification 848,674.  The nitrogen compound may be ammonia, hydrazine, phenyl,-methyl-, 1,2-diphenyl-, or 1-ethyl-2-phenyl-hydrazine, methyl-, ethyl-, propyl-, butyl-, amyl-, benzyl-, dimethyl-, diethyl-, or diphenyl-amine, aniline, N-butyl aniline, 1,2-ethanediamine, cyclohexylamine, N - methyl cyclohexylamine, p-ethoxyethylamine, o-chloroaniline, o-aminophenol, amino acetic acid, 3-amino butanoic acid, methyl aminoethanoate, o-amino acetophenone, 2-amino-2-methyl-1-propanol, hydroxylamine, methyl hydroxylamine, urea, 1 - phenyl semicarbazide, or guanidine. The nitrogen compound as solid, liquid, or gas, should be in excess, and is contacted by any method at room temperature to 1100 DEG C., preferably 700-800 DEG C.  The treated silica may be treated with steam under elevated temperature to remove nitrogen.  The nitrogen compound residue in the silica is in amount stoichiometrically equivalent to the halogen replaced, and the treated silica may be coated with alcohols, amines, or silicone resins.  A large number of organic polymers, in which the pigment may be used, are specified including natural and synthetic rubbers, such as polymers, copolymers, terpolymers, etc., of conjugated dienes, vinyl resins, acrylic resins, carboxyl-containing compounds, olefins, ester urethanes, or silicones.  The polymeric compositions contain usual compounding ingredients, and may contain 25-45% pigment to 75-55% polymer, and are cured.  In Examples:- (1) anhydrous ammonia is passed through halogenated silicon monoxide in a quartz tube at 800 DEG C., and the resulting pigment is mixed with (3) natural rubber, dianilino methane, sulphur, zinc oxide, stearic acid, pine oil, phenylbeta-naphthylamine, didodecylamine, and benzyl thiazyl disulphide.  Specifications 804,991, 804,992 and 828,723 also are referred to.